What is the difference between a colloid and a solution?
A solution is homogenous and 1 phase. A colloid is heterogeneous, and consists of more than 1 phase.
A colloid consists of more than 1 phase - for example, it could be solid in gas (smoke), two immiscible liquid phases (oil/water emulsion), or maybe gas in liquid (shaving foam). The key point is that there is not a single phase but two phases which exist as a stable suspension. Technically, a colloid should have a mean particle size between 1 and 1000